The secret of this workout is "dynamic tension." By using only one set of three-pound dumbbells (hand-held weights) you create your own resistance by flexing and using dynamic tension. Thousands of women have written to me that they have achieved a tight, toned body with this 12-minute a day time investment. Perhaps the most important aspect of this book is its ability to force you to keep your workout and diet up on vacation, on business trips, and when visiting , any time you're away from home. It shows you how to eat around the most impossible home, hotel or business menu. You can do the workout with no weights while traveling by just doing the moves and using the tension.